[Bug-readline] Ctrl-W (erase word) in vi editing-mode has wrong behavior

[John Florian]

I just reported the following on https://bugzilla.redhat.com/show_bug.cgi?id=1477328:

"""

Description of problem:
Ctrl-w now stops at word-breaking characters rather than spaces as it's done for a very long time.

Version-Release number of selected component (if applicable):

readline-7.0-5.fc26.x86_64

How reproducible:
always

Steps to Reproduce:
1. set -o vi
2. ls /etc/hosts.allow^w


Actual results:
Only "allow" is erased in F26.

Expected results:
With F25 and prior the entire path would be erased.


Additional info:
- Only vi mode seems affected.
- I can bind vi-unix-word-rubout to keys other than ctrl-w and get the expected behavior but I can't seem to even kludge ctrl-w into the old behavior, including tricks like "stty werase 00".
- "bind -p" shows the correct mapping.

"""

I'm guessing this is related to the readline-7.0 release and see in the changelog the following:

m.  The default binding for ^W in vi mode now uses word boundaries specified

    by Posix (vi-unix-word-rubout is bindable command name).

I suspect that's a huge hint, but I know what to make of it.  I can successfully bind ctrl-w to vi-unix-word-rubout but I don't get the old behavior.  Is there an older command name that I should be binding to instead?

Please help.  My muscle memory is cramping up bad.